Ch. 3: Thermodynamics

Question 1

Zeroth Law of Thermodynamics

Answer 1

States that objects are in thermal equilibrium when they are at the same temp. Objects in thermal equilibrium experience no net exchange of heat energy.

Question 2

Temperature

Answer 2

Qualitative measure of how hot or cold an object is; quantitatively. It is related to the average kinetic energy of the particles that make up a substance

Question 3

Thermal Expansion

Answer 3

Describes how a substance changes in length or volume as a function of the change in the temp

Question 4

System

Answer 4

A thermodynamic system is the portion of the universe that we are interested in observing

Question 5

Surroundings

Answer 5

Include everything that is not part of the system

Question 6

Isolated systems

Answer 6

Do not exchange matter or energy with the surroundings

Question 7

Closed systems

Answer 7

Exchange energy but not matter with their surroundings

Question 8

Open systems

Answer 8

Exchange both energy and matter with their surroundings

Question 9

State functions

Answer 9

Pathway independent and are not themselves defined by a process. Pressure, density, temp, volume, enthalpy, internal energy, Gibbs free energy, and entropy are all state functions

Question 10

Process Functions

Answer 10

Describe the pathway from one equilibrium state to another. Work and heat are process functions

Question 11

First law of thermodynamics

Answer 11

Statement of conservation of energy: the total energy for the universe can never decrease or increase.

Question 12

Closed system total energy is equal to

Answer 12

The heat flow into the system minus the work done by the system

Question 13

Heat

Answer 13

The process of energy transfer between two objects at different temperatures that occurs until the two objects come into thermal equilibrium (reach the same temperature)

Question 14

Specific heat

Answer 14

Amount of energy necessary to raise one gram of a substance by one degree celsius or one kelvin (water’s is 1 cal/g*K)

Question 15

Heat of transformation

Answer 15

During a phase change, heat energy causes changes in the particles’ potential energy and energy distribution (entropy), but not kinetic energy. Therefore there is no change in temp. This energy is heat of transformation

Question 16

4 special types of thermodynamic systems where a variable is held constant

Answer 16

1. Isothermal processes (temp is constant– change in internal energy is 0), 2. adiabatic processes (no heat is exchanged),
2. isobaric processes (the pressure is held constant),
3. isovolumetric (isochoric) processes (volume is constant and work done on or by system is 0)

Question 17

Second Law of Thermodynamics

Answer 17

States that in a closed system (up to and including the entire universe), energy will spontaneously and irreversibly go from being localized to being spread out (dispersed)

Question 18

Entropy

Answer 18

Measure of how much energy has spread out or how spread out energy has become

Question 19

Microstates

Answer 19

On a statistical level, as the number of available microstates increases, the potential energy of a molecule is distributed over that larger number of microstates, increasing entropy

Question 20

Natural process

Answer 20

Every natural process is ultimately irreversible; under highly controlled conditions, certain equilibrium processes such as phase changes can be treated as essentially reversible